This is one of my favourites.
Returns a subtotal in a list or database. However this does not just add, it can count, average, min max and more.

SUBTOTAL(function_num, ref1, ref2, …)

Function_num is the number 1 to 11 (includes hidden values) or 101 to 111 (ignores hidden values) that specifies which function to use in calculating subtotals within a list.

Ref1, ref2 are 1 to 29 ranges or references for which you want the subtotal.

If there are other subtotals within ref1, ref2,… (or nested subtotals), these nested subtotals are ignored to avoid double counting.
For the function_num constants from 1 to 11, the SUBTOTAL function includes the values of rows hidden by the Hide command under the Row submenu of the Format menu). Use these constants when you want to subtotal hidden and nonhidden numbers in a list. For the function_Num constants from 101 to 111, the SUBTOTAL function ignores values of rows hidden by the Hide command under the Row submenu of the Format menu). Use these constants when you want to subtotal only nonhidden numbers in a list.

The SUBTOTAL function ignores any rows that are not included in the result of a filter, no matter which function_num value you use.

The SUBTOTAL function is designed for columns of data, or vertical ranges. It is not designed for rows of data, or horizontal ranges. For example, when you subtotal a horizontal range using a function_num of 101 or greater, such as SUBTOTAL(109,B2:G2), hiding a column does not affect the subtotal. But, hiding a row in a subtotal of a vertical range does affect the subtotal.

When you are resizing drawing objects in Excel, if you press the Alt key as you drag/resize the object will resize to the cell size.
This is very useful when you are trying to get the exact cell alignment with a text box or chart.

Here is a great tip for people who use number formats a lot. Try selecting a cell with a number and typing CTRL+SHIFT+1 .

This shortcut formats my numbers to #,##0.00 which is the most common number format used where I work.